Corridors longer than _____ feet must have no dead ends in buildings where more than one exit access doorway is required.

In commercial building inspections, the requirement regarding corridors is designed to enhance safety and facilitate evacuation in the event of an emergency. When corridors exceed a certain length, they must be structured to ensure that occupants can evacuate swiftly without encountering dead ends, which can create confusion or hinder escape.

The critical number of feet that determines whether a corridor must have no dead ends is 20 feet. This standard comes from life safety codes and building regulations that aim to minimize unsafe conditions in commercial structures. A corridor longer than 20 feet necessitates careful design to ensure adequate egress routes and avoid potential hazards associated with long corridors, such as becoming trapped or disoriented. This regulation is a vital aspect of building safety and emergency preparedness.

Thus, the correct answer accurately reflects the requirement that corridors longer than 20 feet must not have dead ends, ensuring that multiple exit options are available for occupants.